Red blood cells, platelets and white blood cells, which are blood cells, change in number variously reflecting the condition of the living body. For example, red blood cells are mainly involved in the transportation of oxygen and change in number according to symptoms such as anemia, polycytemia and the like. In acute leukemia, moreover, red blood cells, platelets and neutrophils decrease and, among white blood cells, when blast cells, which are supposed to become granulocytes, become cancerous and blast cells are present in not less than 3%, acute myeloid leukemia develops, and when lymphocytes become cancerous and blast cells are present in less than 3%, acute lymphocytic leukemia develops.
Thus, the ratio of blood cells varies depending on the disease.
Therefore, blood analysis involving counting the blood cells according to the kind thereof, and determining the frequency distribution relating to the number, form, ratio and the like, is an important measurement for diagnosis in medical care and the like.
As methods for counting blood cells in a blood specimen (blood cell counting method), an impedance method utilizing changes in electrical characteristics, flow cytometry which is an optical technique, a light-focused flow impedance method which is a combination of the aforementioned impedance method and flow cytometry and the like are known, and blood cell counting apparatuses (blood analysis apparatuses) configured to perform these methods are also known.
Counting in the field of blood analysis means not only the simple counting of blood cells but also measuring which particles having what volume are present and in what number.
Moreover, a hemolysis treatment, a contraction treatment, a staining treatment and the like are applied as appropriate to a blood specimen to distinguish red blood cells from white blood cells, and further classifying white blood cells, neutrophils, eosinophils, basophils, monocytes and lymphocytes and counting them (what is called the classification of white blood cells into 5 types).
The mechanism of FIG. 1 is the mechanism of the main part of the blood analysis apparatus configured to count red blood cells and classify white blood cells into 5 types. As shown in FIG. 1, when a specimen container 1 containing a blood specimen is set at a predetermined position, a sampling nozzle 2 (a long and thin pipe which is also called a “needle”) moves to suck the blood specimen in the specimen container 1, and discharges the same into each chamber (31, 32, 33, 34) in exclusive blood cell counting part 3, after which a counting device formed in or connected to the chamber obtains measurement data, and a control part (not shown) processes the measurement data and analyzes the frequency distribution and the like. Each blood cell counting part is composed of a chamber, which is a container receiving a blood specimen, and includes the device for performing the above-mentioned impedance method, flow cytometry and light-focused flow impedance method according to the blood cells to be counted, which operates according to the control part (e.g., computer). The obtained count data are sent to the control part. The details of each blood cell counting part are as mentioned below.
The sampling nozzle can move vertically and downwardly-upwardly due to the probe unit 6 provided with a moving mechanism 61 and a horizontally moving mechanism 62. The movements of inserting the sampling nozzle into the specimen container and each chamber to perform sucking and discharge are controlled by the control part (e.g., computer).
In a preferable embodiment, chambers formed to constitute each blood cell counting part include, as shown in FIGS. 1 and 3, BASO chamber 31 in the basophil counting part, a chamber 32 of the blood cell counting part for counting lymphocytes, monocytes, neutrophils and eosinophils, RBC chamber 33 in the red blood cell counting part, and WBC chamber 34 in the white blood cell counting part (for white blood cell counting, HGB analysis).
In the following explanation, the blood cell counting part for counting the aforementioned lymphocytes, monocytes, neutrophils and eosinophils is also referred to as a “LMNE counting part”, taking each first letter from “lymphocyte”, “monocyte”, “neutrophil” and “eosinophil”. Also, chamber 32 in FIG. 1, which is formed in the LMNE counting part, is also referred to as a “LMNE chamber”. In the embodiment of FIG. 3, a flow cell (not shown) is connected to the LMNE chamber 32, and adapted to perform a necessary treatment with a reagent, performing the above-mentioned light-focused flow impedance method in the flow cell, and counting the aforementioned lymphocytes, monocytes, neutrophils and eosinophils.
In FIG. 1, the chamber shown by symbol 7 is a cleaning chamber for blood cell counting wherein the blood adhered to the sampling nozzle (hereinafter to be also referred to as “nozzle”) is washed or cleaned, or an excess blood specimen in the nozzle is discarded.
In the blood analysis apparatus shown in FIG. 1, the nozzle 2, as shown in FIG. 2, sucks a predetermined amount of a blood specimen 100 into its long and thin conduit at one time, and discharges the same into each chamber in the blood cell counting part 3. To be more specific, the blood specimen in the first section A1 of the nozzle is discharged into a WBC chamber 34, the blood specimen in the second section A2 is discharged into a BASO chamber 31, and the blood specimen in the third section A3 is discharged into an LMNE chamber 32.
In each blood cell counting part containing the dispensed blood specimen, the count data specific to each blood cell counting part is obtained under the control of the control part, the count data obtained from each blood cell counting part are processed in the control part (not shown), and each of the object blood cells is analyzed for the frequency distribution and the like.
To precisely perform sucking, dispensing and discharging a predetermined amount of a blood specimen, the nozzle 2 is connected to a quantitative pump (not shown), and a working fluid 110 such as a diluting liquid and the like is filled in a conduit line between the nozzle 2 and the quantitative pump, whereby a sucking force F1 by the quantitative pump and a discharging force F2 can be accurately transmitted to the nozzle (FIG. 2). A predetermined amount of air 120 is interposed between the working fluid 110 and the blood specimen 100, whereby the working fluid 110 is separated from the blood specimen 100 (FIG. 2).
A method and mechanism thereof for dividing the predetermined amount of the blood specimen 100 sucked in the nozzle at predetermined ratios in the longitudinal direction of the conduit and sequentially dispensing the same in the chambers in each blood cell counting part are explained in detail in, for example, JP-A-11-218538.
As mentioned above, a problem associated with sucking a predetermined amount of a blood specimen in a sampling nozzle and dispensing the same in each blood cell counting part is a phenomenon of insufficient sucking of a blood specimen in the nozzle (insufficient specimen-sucking amount, also called sample short). This phenomenon includes not only a simple failure of a blood specimen to reach a predetermined height of the sampling nozzle, but also mixing of air bubble(s) in the middle part of the nozzle to cause insufficient specimen-sucking amount even when the blood specimen has reached a predetermined height of the sampling nozzle.
The insufficient specimen-sucking amount is developed when the amount of a blood specimen in a specimen container is not sufficient and, as the factors on the side of the apparatus, fouling and clogging of the nozzle and piping, operation failure of the driving part and the like.
When an insufficient specimen-sucking amount occurs, the results of blood cell counting in a blood cell counting part, in which a blood specimen is not sufficiently distributed, are different from those that should have been obtained, and may lead to incorrect diagnosis. For example, in the embodiments of FIGS. 1 and 2, when an insufficient specimen-sucking amount wherein the specimen only reaches half way up to a third section A3 of the nozzle is developed, the following occurs. That is, in the LMNE counting part wherein the blood specimen in this section is dispensed, treatments such as mixing with a predetermined quantity of a reagent, hemolysis of red blood cells, staining and fixing of the object blood cell, and transfer thereof to a flow cell are performed in an LMNE chamber and the blood cells are counted. Therefore, the results of counting become lower than those when the specimen suck amount is normal.
Conventionally, insufficiency of specimen has been pointed out as a problem of various analysis apparatuses. Solution to the problem has been sought by taking note of the specimen in a specimen container, and imaging the amount thereof for detection or confirming the sucked amount of the specimen by using a sensor. However, these measures require a new sensor and an increased number of control circuits in the analysis apparatus, thus rendering the apparatus configuration more complicated.
When a blood specimen is sucked with a sampling nozzle, as shown in FIGS. 1 and 2, since stainless steel with high corrosion resistance is used as a material of the nozzle, it is difficult to directly detect the amount of the blood specimen sucked in the sampling nozzle by a sensor.
The problem of the present invention is to provide a blood analysis apparatus provided with a function to determine whether the amount of a blood specimen sucked in a sampling nozzle has reached a predetermined amount or is insufficient by a new technique.